I have had this same issue. I was able to successfully download the underground tunnel entrance (which is way cool!!), with no problems at all, but when I tried to download the transporter arch and the water bridge, I got zipped folders that were either corrupted or empty. Tried these more than once with no luck. Any ideas? I had no issues with extracting the tunnel files, placed them as directed, and all was well. The others seem to have a problem. Appreciate help, as these look like good items to have.